The migration of transistor technology from planar to Fin Field Effect Transistor (FinFET) requires conformal work function layers for multiple threshold voltages. Tuning the work function towards mid-gap can be achieved by adding Al into the work function layers, with different amounts of Al incorporated allowing for different amounts of voltage tuning, without adding physical thicknesses.
Therefore, there is a need in the art for methods of depositing films with controlled work function.